Not Applicable.
1. Technical Field
This invention relates to the field of data communications, and, more particularly, to the field of data communications using unidirectional data transmission.
2. Background Information
At the present time, data communication is accomplished at increasing rates as data communication technology improves. For example, digital subscriber line (DSL) technology is currently employed to provide relatively high speed data communication over existing wire pairs that connect the typical customer premise to a local central office in the current telecommunications system.
In addition to the telephone network, existing cable networks provide many homes with cable television signals. Only a small percentage of the existing cable plant is suitable for high speed, bi-directional data transmission for various applications. The cost of upgrading the cable plant to facilitate more bi-directional data communication is very high.
Even though DSL technology provides significantly higher data communication rates than predecessor technologies, bi-directional DSL data communication requires significant complexity, resulting in higher cost than unidirectional DSL data communication as well as limitations in speed and transmission distance.
The present invention provides for bi-directional data communication technology that avoids the expense of either upgrading existing network wiring (i.e., cable plant) or the complexity of bi-directional digital subscriber line (DSL) data communication.
In particular, the present invention entails a combined cable/DSL modem and method. The combined cable/DSL modem employs unidirectional data transmission over the existing cable plant for downstream data communication, and unidirectional DSL data transmission over the existing wire pairs employed by the telecommunications network in a single data communications loop.
According to one embodiment, a first combined cable/DSL or hybrid modem is located at a customer premise and a second hybrid modem is located at a cable provider premise. Downstream data traffic is transmitted from the second hybrid modem to the first hybrid modem through the existing cable network. Upstream traffic is transmitted from the first hybrid modem to the second hybrid modem across the local loop, which terminates at a central office. The local loop at the central office is coupled to the second modem at the cable provider premise by a direct link. In another embodiment of the present invention employs a digital repeater apparatus at the central office to establish a link between the local loop and the second modem located at the cable provider premise. In yet another embodiment, the second hybrid modem is located at the central office instead of the cable provider premise.
In further embodiments, a single hybrid modem is employed at the customer premise that transmits upstream data across a local loop to a digital subscriber line access multiplexer (DSLAM) which is coupled to a data communications network. The upstream data is then routed by the data communications network to a far data endpoint. Downstream data originating at the far data endpoint is transmitted to a cable transmitter via the data communications network. The downstream data is then transmitted by the cable transmitter to the single hybrid modem via a cable network. In addition, a direct link may be established between the DSLAM and a data memory cache near the cable transmitter. The data memory cache generally stores frequently accessed data from various far data endpoints in the data communications network once downloaded. A request for previously downloaded information may be communicated to the data cache, and, if the requested data is present, the cable transmitter may download such information to the single hybrid modem without downloading the data from a far data endpoint in the data communications network. The direct link may be established, for example, using a hardwire link, a DSL/DSL repeater circuit, or a private network.
The present invention also entails a method for bi-directional data communication, comprising the steps of: receiving a downstream data signal with a cable receiver circuit in a hybrid modem, the downstream data signal being transmitted across a cable network; and, transmitting an upstream data signal with a digital subscriber line transmitter circuit in the hybrid modem, the upstream data signal being transmitted across a local loop.
Other features and advantages of the present invention will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention, as defined by the claims.